|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions|
|Reactions Classified By Substrate → Small-Molecule Reactions|
EC Number: 18.104.22.168
In Pathway: tryptophan biosynthesis
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
Mass balance status: Balanced.
Enzyme Commission Primary Name: tryptophan synthase (indole-salvaging)
Enzyme Commission Synonyms: tryptophan synthase β2
Standard Gibbs Free Energy (ΔrG'° in kcal/mol): -15.4869995 [Latendresse13]
Enzyme Commission Summary:
Most mesophilic bacteria have a multimeric tryptophan synthase complex (EC 22.214.171.124) that forms L-tryptophan from L-serine and 1-C-(indol-3-yl)glycerol 3-phosphate via an indole intermediate. This intermediate, which is formed by the α subunits, is transferred in an internal tunnel to the β units, which convert it to tryptophan. In thermophilic organisms the high temperature enhances diffusion and causes the loss of indole. This enzyme, which does not combine with the α unit to form a complex, salvages the lost indole back to L-tryptophan. It has a much lower Km for indole than the β subunit of EC 126.96.36.199.
Hettwer02: Hettwer S, Sterner R (2002). "A novel tryptophan synthase beta-subunit from the hyperthermophile Thermotoga maritima. Quaternary structure, steady-state kinetics, and putative physiological role." J Biol Chem 277(10);8194-201. PMID: 11756459
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